Highlights

  • Identifying novel plant-derived compounds with anti-inflammatory and anti-diabetic actions.
  • Characterizing novel molecular targets that mediate the actions of dietary compounds and botanicals in inflammation and immunity.
  • Investigating how diet modulates the gut microbiome and mucosal immune responses.
  • Characterizing the modulation of NLRs, LANCL2 and PPARs as molecular targets for naturally occurring and dietary compounds

Ongoing Efforts

NIMML leads a pioneering Nutritional Immunology program aimed at understanding how diet and nutritional factors influence the immune responses, thereby regulating health and disease outcomes.

Highlights

  • Identifying novel naturally occurring compounds with anti-inflammatory properties for the prevention and treatment of IBD.
  • Exploring the role of LANCL2 as a molecular target for anti-inflammatory nutritionals, medical foods and IBD drugs.
  • Investigating the modulation of mucosal immune responses by dietary and nutritional compounds.
  • Characterizing interactions between diet, microbiome and immune response that modulate IBD.

Ongoing Efforts

The NIMML has developed novel nutritional interventions aimed at preventing or treating IBD. In 2004, our Gastroenterology seminal article demonstrated that conjugated linoleic acid ameliorates colitis in mice through a mechanism that requires expression of PPAR g in immune and epithelial cells. The results of that study were validated in a novel pig model of IBD and a human clinical trial inhumans with Crohn’s disease.

Development of Novel Therapies for Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a widespread and debilitating illness characterized by chronic inflammation in the digestive tract. It affects up to 0.5% of the human population in developed countries and numbers are increasing in the developing world. IBD primarily includes two clinical manifestations: Ulcerative colitis (UC) and Crohn’s disease (CD), both of which can sometimes lead to painful and life-threatening complications. The main difference between UC and CD is the location and nature of inflammation. UC is characterized by the presence of chronic and localized inflammation and superficial lesions in the colonic and rectal mucosa, whereas CD is associated with discontinuous and “transmural” lesions of the gut wall which can affect the whole intestine, from mouth to anus, although the majority of the cases start in the terminal ileum. Both UC and CD patients usually go through different stages regarding the intensity and severity of the illness. The disease is considered to be in an active stage when the patients undergo a flare-up of the condition and present severe inflammation. When the inflammation is reduced or absent the disease is considered to be on remission and the patient does not present any symptom.

Cause

IBD is considered an idiopathic illness since its cause remains still unknown. Although genetic, infectious, immunologic, and psychological factors have been considered to influence the development of IBD, the most recent hypothesis suggest that IBD is the result of a body failure to turn off normal immune responses. The gastrointestinal tract becomes inflammed when the immune system tries to fight an invading microorganism or virus. An autoimmune reaction in which the body mounts an immune response towards normal microflora can also result in inflammation that continues without control and can lead to abdominal pain and bloody diarrhea.

Symptoms

IBD symptoms may vary depending on the severity and location of inflammation, ranging from mild to severe and including the following:

  • Abdominal pain and cramping
  • Severe and bloody diarrhea
  • Fever
  • Malnutrition or weight loss
  • Anemia (as a result of blood loss)

In more severe cases of IBD, especially in Crohn’s disease patients, inflammation can result in intestinal complications including the following:

  • Ulceration and bleeding
  • Perforation of the bowel
  • Strictures and obstruction
  • Fistulae and perianal disease
  • Toxic megacolon (acute dilatation of the colon)
  • Inflammation-induced colorectal cancer

Treatment

The aim of IBD treatment is to reduce the inflammation that leads to the mentioned symptoms. The ultimate goal is not only to relief the symptoms but to achieve a long-term remission of the patient. Current treatments for CD include:

  • Corticosteroids (i.e., prednisone and budesonide)
  • Antibiotics
  • Immunomodulators (i.e., azathioprine, 6-mercaptopurine, and methotrexate)
  • The Food and Drug Administration (FDA)-approved anti-tumor necrosis factor-alpha antibody (Infliximab; Remicade®)

Despite evidence that CD therapies have improved, they are modestly successful for the long-term management of the disease and result in significant side effects such as immune suppression, enhanced susceptibility to malignancies, and suppressed resistance against infectious diseases. Moreover, two-thirds to three-quarters of patients with Crohn’s disease will require surgery at some point during their lives, which becomes necessary in Crohn’s disease when medications can no longer control the symptoms. Therefore, there is a need to identify novel and safer therapies for the treatment of IBD. In this regard, and consistent with the concept from bench to bedside, our group has translated the basic scientific understanding of cellular and molecular processes to the clinic through collaborations with Wake Forest University and the Digestive Health Center of Excellence at the University of Virginia. Under a contract from Cognis (now BASF) awarded to the NIMML, we have investigated the ability of conjugated linoleic acid (CLA) to down-regulate intestinal inflammation and ameliorate gut health and we have discovered important new information on the efficacy of CLA in treating patients with CD.

The clinical trial, which was managed as an Investigational New Drug (IND) trial, found that CD patients who took supplementary CLA showed noticeable improvement. CLA was administered as a supplement (6 g/day orally) in thirteen study subjects with mild to moderate CD for 12 weeks and we found a marked improvement in disease activity and quality of life, and importantly, no adverse side effects since CLA was well tolerated by all of the study subjects. Specifically, there was a statistically significant drop in Crohn’s Disease Activity Index (CDAI) from 245 to 187 (P = 0.013) and increase in Inflammatory Bowel Disease Questionnaire (IBDQ) regarding quality of life from 141 to 165 (P = 0.017) on week 12. Moreover, CLA significantly suppressed the ability of peripheral blood CD4+ and CD8+ T cell subsets to produce pro-inflammatory cytokines including IFN-γ, TNF-α and IL-17 and to proliferate at week 12. In summary, CLA represents a promising new supportive intervention for gut inflammation. This is in contrast with the results of human clinical studies using n-3 polyunsaturated fatty acids in IBD that remain largely unimpressive. The present study has shed new light on the clinical potential of this compound and provided insights on the possible mechanisms of immune modulation targeted by CLA in the human system. Based on these results, a larger Phase II double-blind, placebo-controlled, randomized trial with several doses of CLA is warranted.

Collaborators

  • Richard Bloomfeld (Digestive Health Center; Wake Forest University Baptist Medical Center)
  • Stephen J. Bickston (Digestive Health Center of Excellence; VCU Medical Center)
  • Kim Isaacs (Division of Gastroenterology and Hepatology, UNC Department of Medicine)
  • Hans Herfarth (Division of Gastroenterology and Hepatology, UNC Department of Medicine)
  • Paul Yeaton (Division of Gastroenterology, Carilion School of Medicine)
  • Dario Sorrentino (Carilion School of Medicine)

Publications

  • Bassaganya-Riera, J., R. Hontecillas, W. T. Horne, M. Sandridge, H. H. Herfarth, R. Bloomfeld, K. L. Isaacs (2012) Conjugated linoleic acid modulates immune responses in patients with mild to moderately active Crohn’s disease. Clinical Nutrition. 5: 721-727. [ PubMED ]
  • Bassaganya-Riera, J. and R. Hontecillas (2010) Dietary conjugated linoleic acid and n-3 polyunsaturated fatty acids in inflammatory bowel disease. Curr Opin Clin Nutr Metab Care, 2010. 13: p. 569-573. [ PubMED ]
  • Hontecillas, R and J. Bassaganya-Riera (2007) Peroxisome proliferator-activated receptor gamma is required for regulatory CD4+ T cell-mediated protection against colitis. J. Immunol. 178: 2940-2949. [ PubMED ]
  • Bassaganya-Riera, J., and R. Hontecillas (2006) CLA and n-3 PUFA differentially modulate clinical activity and colonic PPAR-responsive gene expression in a pig model of experimental IBD. Clinical Nutrition. 25: 454-65 [ PubMED ]
  • Hontecillas, R., J. Bassaganya-Riera, J. Wilson, D. Hutto, and M. J. Wannemuehler (2005) CD4+ T cell responses and distribution at the colonic mucosa during Brachyspira hyodysenteriae-induced colitis in pigs. Immunology. 115: 127-135. [ PubMED ]
  • Bassaganya-Riera, J., K. Reynolds, S. Martino-Catt, Y. Cui, L. Hennighausen, F. Gonzalez, J. Rohrer, A. Uribe Benninghoff, and R. Hontecillas (2004) Activation of peroxisome proliferator-activated receptor gamma and delta by conjugated linoleic acid mediates protection from experimental inflammatory bowel disease. Gastroenterology. 127: 777-791. [ PubMED ]
  • Hontecillas, R., J.Bassaganya-Riera (2003) Differential requirements for proliferation of CD4+ and gammadelta+ T cells to spirochetal antigens. Cellular Immunol. 224: 38-46. [ PubMED ]
  • R. Hontecillas, D.L. Hutto, D. U. Ahn, J. H. Wilson, M. J. Wannemuehler, and J. Bassaganya-Riera. (2002) Nutritional regulation of bacterial-induced colitis by dietary conjugated linoleic acid. J. Nutr. 132: 2019-2027. [ PubMED ]
  • Bassaganya-Riera, J., R. Hontecillas, D.C. Beitz. (2002) Colonic Anti-inflammatory Mechanisms of Conjugated Linoleic Acid. Clinical Nutrition 21 (6): 451-459. [ PubMED ]

Data Figures

Highlights

  • Identification of novel plant-derived compounds (i.e., resorcinols) from a diverse collection of Madagascar extracts.
  • Identification of naturally occurring botanicals that bind to LANCL2 and activate the LANCL2 pathway.
  • In silico screening of natural product databases through molecular modeling of protein-botanical interactions.

Ongoing Efforts

The NIMML discovered the immune modulatory properties of the plant hormone abscisic acid (ABA) and identified LANCL2 as its molecular target. ABA exerts potent anti-diabetic and anti-inflammatory effects in mouse models of colitis, obesity, type 2 diabetes and atherosclerosis.

Mechanisms of Immune Modulation by Phytochemicals

Funded by a grant from the National Institutes of Health (NIH). 1RO1AT004308 10/2007-09/2011. The goal of this project is to elucidate the mechanisms of immune modulation by abscisic acid (ABA).

Abscisic acid (ABA) is a botanical involved in the regulation of plant growth and a promising immune modulator. ABA activates peroxisome proliferator-activated receptor gamma (PPAR γ) in reporter assays and modulates immune function and inflammation in vivo. The long-term goal of this application is to elucidate the cellular and molecular mechanisms by which ABA modulates immune function. Specific Aim 1 will test the hypothesis that ABA modulates lymphocyte proliferation through a PPAR γ-dependent mechanism. Specific Aim 2 will test the hypothesis that ABA down-modulates monocyte chemoattractant-1 (MCP-1) production through a PPAR γ-mediated blockade of nuclear factor-kappaB (NF-kappaB). The mechanistic understanding of the immune modulatory properties of botanicals such as ABA will aid in the development of more efficacious complementary and alternative medicine approaches for modulating immune function and ameliorating infectious diseases. Our group has developed in vitro screening techniques to characterize novel plant-derived immune modulators and in collaboration with Dr. Bevan at the Department of Biochemistry we are developing in silico screening techniques.

Collaborators

Publications

  • Hontecillas, R., A.J. Guri, U. Wankhade, G. Lopez-Velasco, E.T. McCall, and J. Bassaganya-Riera (2007) Dietary abscisic acid modulates T cell proliferation and cytokine production. FASEB Meetings, Washington, D.C.; (Abstract #4269).

Highlights

  • Identification of PPARs as molecular targets for CLA and conjugated triene fatty acids.
  • Characterization of the anti-inflammatory and immune modulatory mechanisms of CLA, punicic acid and eleostearic acid.
  • Validation of immune modulatory actions of CLA in humans with Crohn's disease

Ongoing Efforts

The NIMML was the first Laboratory to report the immune modulatory properties of conjugated linoleic acid (CLA) in pig models of vaccination and challenge with enteric pathogens. We have also investigated the mechanisms underlying the modulation of immune responses by dietary CLA and n-3 polyunsaturated fatty acids and conjugated triene fatty acids (i.e., catalpic acid, eleostearic acid, punicic acid).

Immune Modulation by Dietary Lipids

Funded by a grants from Bristol Myers Squibb, Loders Croklaan BV and National Pork Board and United States Department of Agriculture. The goal of this project is to characterize the immune modulatory properties and mechanisms of action of dietary lipids.

The following statement has been attributed to Hippocrates, the Father of Medicine “Let food be your medicine, and medicine be your food.” The use of dietary components to prevent or ameliorate diseases, in general, and inflammatory disorders in particular, is best illustrated by the broad range of activity of dietary lipids. For instance, arachidonic acid (AA) is a precursor for proinflammatory lipid mediators, including prostaglandin E2 and leukotriene B4. In contrast, n-3 polyunsaturated fatty acids such as docosahexaenoic (DHA) and epicosapentaenoic (EPA) found in fish oil suppress the production of AA-derived lipid mediators and can be metabolized to anti-inflammatory mediators. Many of these lipid mediators as well as conjugated linoleic acid (CLA) have been characterized as agonists of the nuclear receptor peroxisome proliferator-activated receptor gamma (PPAR g). The Nutritional Immunology Group aims to characterize novel immune modulatory actions of dietary lipids such as CLA and n-3 fatty acids and elucidate their PPAR g-dependent and PPAR g-independent mechanisms of action. This fundamental knowledge is needed for the rational design of nutrition-based interventions against chronic and inflammatory conditions.

Publications

  • Bassaganya-Riera, J., A.J. Guri, A.M. Noble, K.A. Reynolds, J. King, C. Wood, M. Ashby, D. Rai, and R. Hontecillas (2007) Arachidonic acid-and docosahexaenoic acid-enriched formulas modulate antigen-specific T cell responses to influenza virus in neonatal piglets. Am. J. Clin. Nutr. 85: 824-836. [ PubMED ]
  • Bassaganya-Riera, J, and Hontecillas, R. Modulation of CD8+ T cell Responses by Conjugated Linoleic Acid. In: Pariza, MW, Yurawecz, P, eds. Advances in CLA Research, Volume 3, pp 157-174; American Oil Chemists Society Press, Champaign, IL, 2006.
  • O’Shea, M., J. Bassaganya-Riera, and I. Mohede. (2004) Immunomodulatory Properties of Conjugated Linoleic Acid. Am. J. Clin. Nutr. 79 (6): 1199S-1206S. [ PubMED ]
  • Bassaganya-Riera, J., Pogranichnyi, R., Jobgen, S.C., Halbur, P.G., Yoon, K-Y, O’Shea, M., Mohede, I., Hontecillas, R. (2003) CLA Ameliorates Viral Infectivity in a Pig Model of Virally Induced Immunosuppression. J. Nutr. 133: 3204-3214. [ PubMED ]
  • Bassaganya-Riera, J., R. Hontecillas, D. R. Zimmerman, and, M. J. Wannemuehler. (2002) Long-term influence of lipid nutrition on CD8+ responses to viral and bacterial antigens. Vaccine 20: 1435-1444. [ PubMED ]
  • Bassaganya-Riera, J., R. Hontecillas, D. R. Zimmerman, and, M. J. Wannemuehler. (2001) Dietary conjugated linoleic acid modulates phenotype and effector functions of porcine CD8+ lymphocytes. J. Nutr. 131: 2370-2377. [ PubMED ]
  • Bassaganya-Riera, J., R. Hontecillas, K. Bregendahl, M. J. Wannemuehler, and D. R. Zimmerman. (2001) Effects of dietary conjugated linoleic acid in nursery pigs of dirty and clean environments on growth, empty body composition and immune competence. J. Anim. Sci. 79: 714-721. [ PubMED ]

Highlights

  • Computational modeling of host-microbiota-probiotic interactions.
  • Characterization of metabolic pathways in the microbiota controlling the host immune response.
  • Characterizing interactions between diet and gut microbiota in shaping the host immune response.

Ongoing Efforts

The NIMML investigates the relationship between diet, gut microbiome and host immune responses. We have focused our initial efforts on characterizing how VSL#3 probiotic bacteria modulate mucosal immune responses to ameliorate IBD.

The intestinal microflora

What is it?

Immediately after birth, all body surfaces of the newborn, including the gastrointestinal tract, are colonized with bacteria. The colonization of the human body by microorganisms is natural and indispensable for life. Bacteria colonizing the gastrointestinal canal are known as “intestinal microflora”.

Which are its functions?

Dietary fibers from fruits and vegetables cannot be digested by the enzymes in the stomach. Therefore, such molecules get to the intestine, where they are broken down by the microflora. The resulting products, also so-called short-chain fatty acids (SCFA) such as butyric acid, lactic acid or acetic acid, are very energy-rich and essential for the nourishment and supply of blood to the colonic mucosa. Some of them also promote the dilation of blood vessels allowing an optimal supply of blood to the intestines, as well as prevent cell death and intestinal inflammation, among other functions.

The intestinal microflora and the immune system

The immune system protects the body from disease-causing bacteria. The normal healthy microbiota contributes to the body protection by settling and occupying the habitats inside the intestine and the intestinal mucosa, thus preventing the initial direct contact between the pathogens and healthy intestinal cells. Moreover, intestinal microorganisms are important for the development and maintenance of the immune since system since these harmless bacteria train the immune cells to prepare and combat pathogens. Disturbances in the microflora are involved in the development of several diseases such as irritable bowel syndrome and inflammatory bowel diseases (IBD).

Inflammatory bowel disease

IBD is a widespread and debilitating illness characterized by chronic inflammation in the digestive tract. It affects up to 0.5% of the human population in developed countries and numbers are increasing in the developing world. IBD primarily includes two clinical manifestations: Ulcerative colitis (UC) and Crohn’s disease (CD), both of which can sometimes lead to painful and life-threatening complications.

Cause

The development of IBD depends on the combination of several factors rather than one factor solely. For instance, changes in hereditary disposition seem to be important, as well as environmental factors including smoking or harmful chemicals. Disturbances in the immune system have also been detected in IBD patients. In these cases, there is a loss of the natural tolerance of the mucosal immune system towards the intestinal microflora, thus resulting in excessive autoimmune reactions against the body’s own intestinal tissues. A disturbed intestinal microbiota is also usually involved in the development of IBD. An alteration of the intestinal microorganisms can have a great impact on the natural balance and state of health. In this regard, IBD patients have reduced levels of beneficial intestinal microorganisms, whereas potentially disease-causing microorganisms, also called pathogens, are increased. Pathogens are not the cause of IBD but a consequence since they settle more easily in inflamed mucosa and are therefore more commonly detected in IBD patients than in healthy individuals. Changes in the intestinal microflora also alter the supply of essential nutrients such as short chain fatty acids to the mucosa, thus resulting in intestinal cell death due to malnourishment. In this regard, two promising approaches for the treatment of IBD are the administration of bacterial metabolic products or prebiotics, and the direct administration of bacterial strains which belong to the intestinal microflora or probiotics.

Potential treatments

Prebiotics

Prebiotics are non-digestible oligosaccharides, defined as “selectively fermented ingredients that allow specific changes, both in the composition and/or activity of the gastrointestinal microflora that confers benefits upon host wellbeing and health”. The use of specific prebiotics to stimulate growth and activity of intestinal microbiota has been successful in animal models of colitis, although knowledge regarding their mechanism of action is limited. NIMML has recently demonstrated the efficacy of resistant starch (RS), soluble corn fiber (SCF) and inulin to ameliorate clinical disease and prevent inflammatory lesions in an IL-10-/- mouse model of IBD [1]. The protective effect of RS-75 was proposed to be associated with an increase in SCFA production, butyrate in particular. We found that the preventive effect of RS-75 is also associated with increased spleen and Peyer’s patches percentages of regulatory T cells (Treg), which modulate the immune system, maintain the tolerance to self-antigens, and abrogate autoimmune disease. RS-75 also reduced the production of interferon (IFN) γ, suggesting a suppression of the pro-inflammatory Th1 cell phenotype in the gut. Dietary RS-75 and inulin supplementation modulate the Treg compartment causing changes in the gut’s microbial ecology, resulting in increased butyrate levels that subsequently activate anti-inflammatory pathways.

Probiotics

Probiotics are live microbial supplements which beneficially impact on host health. These products rely on introducing particular exogenous bacterial strains into the intestinal microflora. Several probiotics have been shown to be efficacious in the treatment of IBD, specially the commercially available mixture VSL#3, the Escherichia coli strain Nissle 1917 and several Lactobacillus species.

VSL#3 has demonstrated efficacy in patients with ulcerative colitis and in animal models of colitis. Interestingly, some of the strains present in VSL#3 are able to produce conjugated linoleic acid (CLA) and conjugated linolenic acid (CLnA) isomers in vitro from linoleic acid or alpha-linoleic acid, both of which have been shown to have string anti-inflammatory efficay. In this line, we recently provided novel in vivo evidence that VSL#3 administration changes microbial diversity and local CLA production which results in the activation of anti-inflammatory pathways in different models of experimental colitis in mice [2].

Publications

1. Bassaganya-Riera, J., et al., Soluble fibers and resistant starch ameliorate disease activity in interleukin-10-deficient mice with inflammatory bowel disease. J Nutr, 2011. 141(7): p. 1318-25. [PubMED]
2. Bassaganya-Riera, J., et al., Probiotic bacteria produce conjugated linoleic acid locally in the gut that targets macrophage PPAR gamma to suppress colitis. PLoS One, 2012. 7(2): p. e31238. [PubMED]